We should certainly do that, there's lots of valuable information that
can and therefore should be kept. The interesting point is: What
algorithm do we use to decide on what is a clean override and what is a
derivation? Something like Levenshtein distance might be worth
considering. There's also a point in just saying every change can be
kept, as the changer apperently has some knowledge, otherwise he
couldn't do the change (ok, that's not true with typo correction, but
the question is: How many such cases are there?), but we could do that
just like the current decision on splits and merges: Keep it and if
anyone complains, remove it. That would most certainly be ok for most
cases and has the advantage of being really easy.
Dominik